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diff --git a/docs/report/introduction/methodology_reconf.rst b/docs/report/introduction/methodology_reconf.rst deleted file mode 100644 index 976cd7a6a3..0000000000 --- a/docs/report/introduction/methodology_reconf.rst +++ /dev/null @@ -1,75 +0,0 @@ -.. _reconf_tests: - -Reconfiguration Tests -^^^^^^^^^^^^^^^^^^^^^ - -.. important:: - - **DISCLAIMER**: Described reconf test methodology is experimental, and - subject to change following consultation within csit-dev, vpp-dev - and user communities. Current test results should be treated as indicative. - -Overview -~~~~~~~~ - -Reconf tests are designed to measure the impact of VPP re-configuration -on data plane traffic. -While VPP takes some measures against the traffic being -entirely stopped for a prolonged time, -the immediate forwarding rate varies during the re-configuration, -as some configurations steps need the active dataplane worker threads -to be stopped temporarily. - -As the usual methods of measuring throughput need multiple trial measurements -with somewhat long durations, and the re-configuration process can also be long, -finding an offered load which would result in zero loss -during the re-configuration process would be time-consuming. - -Instead, reconf tests first find a througput value (lower bound for NDR) -without re-configuration, and then maintain that ofered load -during re-configuration. The measured loss count is then assumed to be caused -by the re-configuration process. The result published by reconf tests -is the effective blocked time, that is -the loss count divided by the offered load. - -Current Implementation -~~~~~~~~~~~~~~~~~~~~~~ - -Each reconf suite is based on a similar MLRsearch performance suite. - -MLRsearch parameters are changed to speed up the throughput discovery. -For example, PDR is not searched for, and the final trial duration is shorter. - -The MLRsearch suite has to contain a configuration parameter -that can be scaled up, e.g. number of tunnels or number of service chains. -Currently, only increasing the scale is supported -as the re-configuration operation. In future, scale decrease -or other operations can be implemented. - -The traffic profile is not changed, so the traffic present is processed -only by the smaller scale configuration. The added tunnels / chains -are not targetted by the traffic. - -For the re-configuration, the same Robot Framework and Python libraries -are used, as were used in the initial configuration, with the exception -of the final calls that do not interact with VPP (e.g. starting -virtual machines) being skipped to reduce the test overall duration. - -Discussion -~~~~~~~~~~ - -Robot Framework introduces a certain overhead, which may affect timing -of individual VPP API calls, which in turn may affect -the number of packets lost. - -The exact calls executed may contain unnecessary info dumps, repeated commands, -or commands which change a value that do not need to be changed (e.g. MTU). -Thus, implementation details are affecting the results, even if their effect -on the corresponding MLRsearch suite is negligible. - -The lower bound for NDR is the only value safe to be used when zero packets lost -are expected without re-configuration. But different suites show different -"jitter" in that value. For some suites, the lower bound is not tight, -allowing full NIC buffers to drain quickly between worker pauses. -For other suites, lower bound for NDR still has quite a large probability -of non-zero packet loss even without re-configuration. |